Laboratory instrumentation of orthoses and prostheses can be used to objectively assess the functional differences between various componentry designs and to measure the effect of an orthosis or prosthesis on the outcome of treatment. This article describes the electromechanical transducers and instrumentation systems that may be used to accomplish these tasks. The transducers are grouped in the following categories: stress and strain, linear and angular displacement, acceleration, force, pressure, temperature and humidity. Examples of transducer applications, instrumentation selection and integration are described.